NAME¶
memmem - locate a substring
SYNOPSIS¶
#include <string.h>
void *memmem(const void *haystack, size_t haystacklen,
const void *needle, size_t needlelen);
DESCRIPTION¶
The
memmem() function finds the start of the first occurrence of the
substring
needle of length
needlelen in the memory area
haystack of length
haystacklen.
RETURN VALUE¶
The
memmem() function returns a pointer to the beginning of the
substring, or NULL if the substring is not found.
This function is a GNU extension.
BUGS¶
This function was broken in Linux libraries up to and including libc 5.0.9;
there the `needle' and `haystack' arguments were interchanged, and a pointer
to the end of the first occurrence of
needle was returned. Since libc
5.0.9 is still widely used, this is a dangerous function to use.
Both old and new libc's have the bug that if
needle is empty
haystack-1 (instead of
haystack) is returned. And glibc (2.0.5)
makes it worse, and returns a pointer to the last byte of `haystack'.
Hopefully this will be fixed. For the time being,
memmem() should not
be used with an empty `needle'.
SEE ALSO¶
strstr(3)